In a given elevator system or environment, one or more sources may be used to provide power. For example, FIG. 1A shows an architecture or circuit 100 for an elevator system. The architecture 100 may include a battery 102 serving as a source of power for a motor 104, such as a permanent-magnet synchronous motor (PMSM). An inverter 106, denoted by the boxed components in FIG. 1A, may be used to generate currents for the motor 104.
The battery 102 may be a lead acid battery and may nominally provide forty-eight volts (48V). As shown in FIG. 1A, the negative terminal of the battery 102 may be grounded. The battery 102 may be charged by a charger 108.
A number of issues may be associated with the architecture/circuit 100 of FIG. 1A. For example, excessive regenerated energy may be consumed in the form of heat via a dynamic braking resistor (DBR) 110 and a dynamic braking transistor (DBT) 112. The charge acceptance rate of the battery 102 may be low. The battery 102 may be ill-suited to provide for instantaneous power capability. A large drop of voltage may be experienced across a capacitor 114 at the “DC link” node or bus, which may result in a lower motor voltage and higher currents, degrading performance in terms of speed and energy efficiency.
Poor travel efficiency may be realized due to DBR, excessive charging rate for batteries and other losses caused by high current levels. Only A variable speed (e.g., minimum 0.63 m/s and maximum 1 m/s) may be realized at competitive cost, with a maximum rise of 21 m and a maximum load of 630 Kg, which may be ill-suited to many markets (e.g., India, Brazil, China, etc.).